The first objective of this research is to analyze the promoter of the alpha-galactosidase A gene in order to investigate the factors that control the expression of this gene in particular, and of this class of genes in general. The levels of lysosomal enzymes are known to vary widely, at least in rodents, during organ development and during changes in the number of lysosomes within a given cell. Antigenic stimulation of immune cells results in a dramatic increase in lysosomal enzyme levels. It is not known if these changes occur at the level of transcription or posttranscriptionally. In addition, mechanisms exist to coordinately regulate the levels of this class of enzymes, since the relative ration of one enzyme to another remains relatively constant, although the absolute levels of the enzymes may vary widely. We have recently isolated a genomic clone containing the promoter for the human alpha-galactosidase A, which is the first genomic clone isolated to date for any lysomal hydrolase, and it should be valuable for the proposed studies of gene regulation. The second objective of this research is to pursue the development of one possible strategy for the treatment of Fabry disease, a prototype inherited metabolic disorder. Previous studies have demonstrated the ability of exogenous alpha-galactosidase A to correct the metabolic defect in Fabry fibroblasts, and clinical trials have suggested the potential effectiveness of enzyme replacement. Human alpha-galactosidase A produced in bacteria, yeasts, and baculovirus will be evaluated using a cell culture system for enzyme replacement in Fabry disease. The cloned cDNA for alpha-galactosidase A will be introduced into Fabry cells in culture to monitor its integration and expression.